JPH1048590A - Projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector being reduced temperature rise of a polarizing plate and a light bulb, and preventing them from deteriorating, and also being of a high quality. SOLUTION: This projector comprises approximately a metal halide lamp 1, two dichroic mirrors 7 and 12 separating emitted light from the metal halide lamp 1 into three color light, three liquid crystal light bulbs 16, 20, and 24 modulating each of the three color light, tow sheets of dichroic mirrors 26 and 29 synthesizing the color light modulated by the liquid crystal light bulbs 16, 20 and 24, and a projection lens 32 projecting a synthesized image. Polarizing plats 15, 19, and 23 are combined with a polarizing plate fixing glass 14, and this permits to prevent the polarizing plates 15, 19, and 23 from being deformed due to heat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical structure of a projector.

[0002]

2. Description of the Related Art A conventional liquid crystal projector is disclosed in
As in -247720, it was composed of a light source, a first dichroic mirror group for three primary color spectroscopy, an image forming element, a second dichroic mirror group, and a projection lens. In addition, a liquid crystal projector configured to insert a cold mirror between the light source and the first dichroic mirror group and to allow only visible light of the light rays emitted from the light source to enter the first dichroic mirror group is also provided. It is commercially available.

[0003]

However, the prior art described above has a problem that the temperature rise of the liquid crystal light valve or the polarizing plate disposed between the liquid crystal light valve and the light source cannot be sufficiently suppressed. The reason for this is that a metal halide lamp has begun to be used as a light source of a liquid crystal projector instead of a conventionally used halogen lamp. Since the conventional halogen lamp is a lamp utilizing high-temperature light emission of tungsten, a large amount of infrared light is emitted, and the temperature of a polarizing plate or a liquid crystal light valve that absorbs the infrared light increases. Therefore, the conventional concept of using only visible light using a cold mirror was very effective when using a halogen lamp. However, since the metal halide lamp utilizes the emission of a metal element in an arc, infrared rays and the like are weak and visible light is very strong. The strong visible light is absorbed by the polarizing plate and the liquid crystal light valve, and thus the temperature rises. This increase in temperature may cause deterioration of the polarizing plate and the liquid crystal light valve.

Accordingly, the present invention is intended to solve such a problem. It is an object of the present invention to prevent a rise in the temperature of a polarizing plate or a light valve, to prevent deterioration of the polarizing plate or a light valve, and to improve the image quality. It is to provide a projector.

[0005]

According to the present invention, there is provided a light source, a first polarization selection element for absorbing light of a specific polarization component among light emitted from the light source, and a first polarization selection element. A light valve that modulates transmitted light, a second polarization selection element that absorbs light of a specific polarization component of the light emitted from the light valve, and projects light that has passed through the second polarization selection element Wherein the first polarization selection element is provided at a position distant from the light valve, and is attached to a fixed plate made of a light-transmitting plate material. I do.

The present invention also provides a light source, color light separating means for separating light emitted from the light source into red, blue, and green light, three light valves for modulating the respective color lights, and A projector comprising: a color light combining unit that combines the color lights modulated by the two light valves; and a projection unit that projects the light combined by the color light combining unit, the light incident surface side of each of the light valves. Is provided with a polarization selection element that absorbs light of a specific polarization component, the polarization selection element is provided at a position away from the light valve, and is attached to a fixed plate made of a light transmitting plate material. It is characterized by the following.

[0007]

FIG. 1 is a plan view showing an embodiment of the present invention. 1 is a metal halide lamp as a light source, 2
Is a reflection plate, 3 is a glass plate, 4 is a glass plate case, 5 is a radiation fin, 6 is a heat ray cut filter, 7 is a green light reflection dichroic mirror, 8 is a mirror fixing plate, 9, 10 is a condenser lens, and 11 is a condensing lens. Mirror, 12 is a red light reflecting dichroic mirror, 13 is a mirror fixing plate, 14, 18, and 22 are polarizing plate fixing glasses, 15, 19, and 23 are polarizing plates,
20 and 24 are liquid crystal light valves, 17, 21 and 25 are holes provided in the lower light guide 31, 26 is a red light reflecting dichroic mirror, 27 is a mirror fixing plate, 28 is a mirror, 29 is a yellow light reflecting dichroic mirror, Reference numeral 30 denotes a mirror fixing plate, 31 denotes a lower light guide, and 32 denotes a projection lens. Reference numerals 41, 42, and 43 denote polarizing plates, and reference numeral 49 denotes a fan.

FIG. 2 is a perspective view showing an embodiment of the present invention. 33 is a fan, 34 is an upper light guide, 35
Is a focus adjustment screw, 36 is a horizontal adjustment screw, 37
Denotes a vertical adjustment screw, and 38 denotes a focus adjustment screw.

The structure of the projector of this embodiment is as follows. A metal halide lamp 1 as a light source is fixed to a reflection plate 2, and most of the light emitted from the metal halide lamp 1 is reflected on the opening-side front surface of the reflection plate 2. Among them, infrared rays are reflected by the heat ray cut filter 6 provided with the infrared reflection coat, and only visible light is transmitted and emitted. In addition, it has been confirmed that this infrared reflection coat reflects most of ultraviolet rays.

A glass plate 3 fixed in a glass plate case 4 is provided between the heat ray cut filter 6 and the metal halide lamp 1. Assuming that the refractive index is n, the glass plate 3 is 90 ° -ATN (1 / n) with respect to light rays.
With this inclination, the polarization component of a plane perpendicular to the plane including the light ray and the normal of the glass 3 is reflected. With one glass plate,
Since about 15% of the polarized light component is reflected, a considerable amount of polarized light component can be reflected if several sheets are used in combination.

The purpose of removing the predetermined polarized light component is to suppress the temperature rise of the polarizing plates 15, 19, and 23. Usually, the liquid crystal projector obtains linearly polarized light from the elliptically polarized light by the polarizers 15, 19, and 23, and then causes the liquid crystal light valves 16, 20, and 24 to emit the linearly polarized light.
The polarizing plates 41, 42, and 43 again take out only the linearly polarized light component. Liquid crystal light valve 16, 2
At 0 and 24, the magnitude of the flashing angle is controlled by an electric signal to change the amount of light passing through the polarizing plates 41, 42 and 43. Thus, in a liquid crystal projector, 1
Only the polarized light of the type is used, and the polarized light component orthogonal to the polarized light is absorbed by the first polarizers 15, 19, and 23 and becomes heat. The temperature rise of the polarizing plates 15, 19, and 23 due to this,
With a 150 W metal halide lamp 1, the temperature reaches 100 ° C., and the polarizing plate is burned. Therefore, the glass plate 3
By setting the incident light beam to the Brewster angle, unnecessary polarization component light is removed, and the polarizing plates 15, 19, and 23 are used.
Protects from heat.

Here, the method of arranging the glass plate 3 is as follows.
As shown in FIG. 3, a method in which one glass plate covers the entire range of the optical path has been conventionally proposed. 44 is a metal halide lamp as a light source, 45 is a reflector, and 46 is a glass plate. In this example, since the length of the glass plate 46 is large, the distance between the metal halide lamp 44 and the liquid crystal light valve is long, and there is a problem that light is not collected by the liquid crystal light valve and the brightness is reduced. Was. In addition, there is a problem that the size of the entire apparatus is increased.

Therefore, in the projector shown in this embodiment, the distance between the metal halide lamp 1 and the liquid crystal light valves 16, 20, and 24 is shortened by arranging the glass plate 3 in a V-shape to facilitate light collection.

FIG. 4 shows an example of the configuration from the light source to the dichroic mirror group. 44 is a metal halide lamp, 45 is a reflection plate, 47 is a glass plate, and 6 is a heat ray cut filter. The glass plate 47 is inclined by Brewster's angle with respect to the incident light beam. In this example, the number of the glass plates 47 may be increased in the central portion where the light amount is the largest, and the glass plate 47 may be eliminated or reduced in the peripheral portion where the light amount is small. By doing so, there is an effect that a decrease in the amount of light at the periphery can be prevented, and a large amount of unnecessary polarized light components can be removed at the center where heat is most concentrated.

FIG. 5 shows another configuration example from the light source to the front of the dichroic mirror group. 48 is a glass plate.
In the example shown in this figure, the glass plate 48 is further divided. Therefore, the metal halide lamp 4 as a light source
The distance between the liquid crystal light valve 4 and the liquid crystal light valve becomes very short, so that the light is easily condensed on the liquid crystal light valve, and a bright projected image can be obtained. Also, with the miniaturization of equipment,
By improving portability, applications can be expanded and costs can be reduced.

Also in this example, it is possible to increase the number of glass plates 48 nearer the center and to reduce the number of glass plates at the periphery. With such a configuration, there is an advantage that a rise in temperature in the central portion where heat protection is most required can be suppressed, and a decrease in the amount of light in the peripheral portion can be suppressed.

In the examples shown in FIGS. 1, 4 and 5, if optical glass such as crown glass is used as the glass plate, there is no problem in terms of transmittance and heat resistance. However, as shown in these figures, the hot-wire filter 6 is connected to the metal halide lamps 1 and 44 and the glass plates 3, 47 and 4.
When the temperature is between 8 and 8, the temperature rise of the glass plate can be suppressed.
Therefore, soda glass and white plate glass, which are not so high in heat resistance, can also be used as a material for these glass plates 3, 47, and 48. Soda glass, white plate glass, and the like have a very low material cost compared to optical glass, and thus greatly reduce costs.

In the example shown in FIG. 1, the fan 49 is connected to the metal halide lamp 1, the heat ray cut filter 6, and the glass plate 3.
It is arranged in parallel with. This aims at efficiently cooling the metal halide lamp 1 as a heat source, the heat ray cut filter 6 as a heat insulating material, and the glass plate 3 with one fan 49. As a result, most of the heat-generating components can be removed before light rays enter the dichroic mirror group. Further, the heat can be discharged outside the apparatus by the fan 49. Therefore, the liquid crystal light valve 16,
It is possible to suppress the temperature rise of the optical elements 20, 24 and the polarizing plates 15, 19, 23, and to improve the performance and reliability of these optical elements.

FIG. 6 shows still another configuration example from the light source to the front of the dichroic mirror group. 6 is a heat ray cut filter, 50 is a glass plate 51 is a fan. In this embodiment, the heat ray cut filter 6 is installed on the opposite side of the glass plate 50 from the metal halide lamp 44. Therefore, the light emitted from the light source reaches the heat ray cut filter 6 after one of the linearly polarized light components is removed by the glass plate 50, so that the temperature rise is reduced.

The heat ray cut filter 6 is usually made by multi-coating an optical glass with a dielectric thin film. Since the thin film may peel off when exposed to high heat, it needs to be cooled by the fan 49 as in the example shown in FIG. In addition, the glass substrate itself must be a high-grade glass substrate that requires heat resistance of 400 ° C. or higher.

However, in the example shown in FIG. 6, since the temperature rise of the heat ray cut filter 6 is small, the peeling of the dielectric thin film due to heat can be reduced. Further, since the heat resistance of the glass base material can be considerably reduced, the base material becomes cheaper and the cost can be reduced. On the other hand, since the glass plate 50 also has an angle of about 60 ° C. with respect to the light beam, a portion of the glass plate 50 does not become particularly high in temperature, and it is possible to use glass having low heat resistance. Since the reflectance of the linearly polarized light component of the glass plate 50 is about 15% per sheet, the greater the number, the greater the effect. On the other hand, the cost increases in proportion to the number of sheets. Therefore, there is a great merit that glass with low heat resistance and low cost can be used.

In this embodiment, the glass plates 3, 50
Are arranged in a V-shape with the light source direction at the top. The glass plates 3 and 50 arranged in this way also serve to condense light beams by refracting them toward the center. When the reflection plates 2 and 45 are larger than the liquid crystal light valves 16, 20 and 24, this light-collecting effect is important for brightening the screen.

Further, with this arrangement, the light reflected by the glass plates 3 and 50 also goes to the outside, so that the heat radiation effect is large. In particular, in the example shown in FIG.
The front surface of 5 does not block the heat ray cut filter 6,
Since only the V-shaped glass plate 50 is provided, air circulation around the metal halide lamp 44 is good. Therefore, the cooling effect of the lamp by the fan 51 is great, and the life of the lamp can be extended.

Further, in this embodiment, the glass plate 3 is installed in the glass plate case 4. Glass plate case 4
Functions not only to fix the glass plate 3 but also to receive reflected light from the glass plate 3 and convert it into heat and emit it. The material of the glass plate case 4 is a blackened metal such as black aluminum having good heat dissipation. The glass plate case 4 is placed on the lower light guide 31 and fixed. Further, fins 5 are attached to portions of the outer wall of the glass plate case 4 to which light reflected from the glass plate 3 shines. This is intended to increase heat radiation from the glass plate case 4. Also,
The use of the glass plate case 4 prevents heat from being directly transmitted to the upper and lower light guides 31 and 34. In this case, if a heat insulating spacer is arranged between the glass plate case 4 and the lower light guide 31, the heat is more completely shut off.

The glass plate 3 may be directly fixed to the lower light guide 31 without being installed in the glass plate case 4. In this case, there is a merit that the optical axis alignment with the dichroic mirror group becomes easy.

Next, a dichroic mirror group in the projector according to the present embodiment will be described. Here, the group of dichroic mirrors refers to the dichroic mirrors from the green light reflecting dichroic mirror 7 to the yellow light reflecting dichroic mirror 2.
9 dichroic mirrors, condenser lenses, polarizing plates,
This is a part constituted by a liquid crystal light guide. These dichroic mirror groups are fixed to the upper light guide 34 and the lower light guide 31, as shown in FIG. Further, a fan 33 is provided below the lower light guide 31 for cooling the dichroic mirror group.

The light emitted from the metal halide lamp 1 is separated into three colors of green, red and blue by a green light reflecting dichroic mirror 7 and a red light reflecting dichroic mirror 12 and enters the liquid crystal light valves 16, 20 and 24. . On the other hand, the video signal input to the liquid crystal projector is decomposed into green, red, and blue signals, converted into liquid crystal drive signals, and then input to the liquid crystal light valves 16, 20, and 24. With these, the liquid crystal light valve 16,
At 20 and 24, original images for green, red and blue are formed, respectively. These original images are combined by a red light reflecting dichroic mirror 26 and a yellow light reflecting dichroic mirror 29 and projected through a projection lens 32.
The above is the main operation of the dichroic mirror group.

In the dichroic mirror group having the above structure, the liquid crystal light valve 16 is a light valve that modulates green light, and the liquid crystal light valve 24 is a light valve that modulates blue light, thereby increasing the yield of liquid crystal light valves and reducing costs. Can be achieved. This will be described.

As for the relationship between the liquid crystal light valves 16, 20, and 24, the liquid crystal light valves 16, 24 may have the same structure, and the liquid crystal light valve 16, 20 must have a mirror-inverted structure. On the other hand, a liquid crystal light valve is a group of fine pixels driven by tens of thousands of transistors. Therefore, pixels (defects) that cannot be driven are likely to be formed. For a liquid crystal projector, it is necessary to make this defect as inconspicuous as possible. As a method therefor, a method is conceivable in which a light valve that modulates green light has few defects and a light valve that modulates blue light allows defects. This is because the human eye is very sensitive to green and relatively insensitive to blue. Therefore, when a liquid crystal light valve is manufactured, if the liquid crystal light valve 24 that modulates blue light is used for those having many defects, and the liquid crystal light valve 16 that modulates green light is used for those having few defects, it cannot be used due to defects. The number of liquid crystal light valves is considerably reduced. Therefore, the yield of the liquid crystal light valve is substantially improved, and the cost can be reduced. This effect is very large considering that the yield among the factors determining the price of the liquid crystal light valve cannot be ignored.

Inducing blue light to the position of the liquid crystal light valve 24 is also effective in cooling the polarizing plate 23 and the liquid crystal light valve 24. This is because blue light has a short wavelength and therefore a large energy, and the temperature rise due to light absorption by the polarizing plate is the largest.

Here, each of the liquid crystal light valves 16, 20,
A fan 33 is provided below the lower light guide 31 to promote cooling of the heat generated in 24. However, since the three liquid crystal light valves are arranged in a crank shape, it is difficult to efficiently cool the three liquid crystal light valves simultaneously with only the small fan 33.
That is, while the liquid crystal light valves 16 and 24 and the polarizing plates 15 and 23 arranged near the outer periphery of the fan 33 are efficiently cooled, the liquid crystal light valve 20 and the polarizing plate 19 arranged near the center are cooled efficiently. Cooling is not very efficient.

Therefore, it is preferable to use the liquid crystal light valve 24 for blue light modulation in terms of cooling efficiency.
The performance and reliability of the polarizing plate 23 and the liquid crystal light valve 24 are greatly improved.

In the metal halide lamp 1, since the green light component is generally large in the luminescent component, the temperature of the liquid crystal light valve 16 tends to be high.
The liquid crystal light valve 16 for modulating the green light is also arranged on the outer periphery of the fan 33 to enhance the cooling effect.

Next, the structure of the polarizing plate in the dichroic mirror group of FIG. 1 will be described.

Generally, as shown in FIG. 7, a polarization component parallel to a plane including a normal line and a light traveling direction with respect to a reflection plane is called a P component, and a polarization component perpendicular to the plane is called an S component. And
As shown in FIG. 8, the characteristics of the green light reflecting dichroic mirror 7, the red light reflecting dichroic mirror 12, the red light reflecting dichroic mirror 26, and the yellow light reflecting dichroic mirror 29 generally differ between S-polarized light and P-polarized light. In the example shown in FIG. 1, the liquid crystal light valves 16, 20,
Polarizers 15, 41, 19, 42, 23, 4 before and after 24
Two types of optical systems are possible depending on the directions of the three absorption axes.

First, the case where the absorption axes of the front and rear polarizing plates are substantially parallel will be described. In this case, the polarizing plate 15,
Dichroic mirrors in front of 19 and 23 and polarizing plate 4
In the dichroic mirror after 1, 42 and 43, the polarization direction is the same. S-polarized light is used because the characteristics of the yellow light reflecting dichroic mirror 29 are better for S-polarized light than for P-polarized light. That is, as shown in FIG. 8, the yellow light reflecting dichroic mirror 29 has a poor reflectance in a long wavelength band, so that the P-polarized light component cannot be used. Therefore, all the dichroic mirrors use the S-polarized light indicated by the dotted line in FIG. At this time, a part of the P-polarized light is reflected by the glass plate 3,
Removed.

However, the rest is absorbed by the polarizers 15, 19, and 23 and becomes heat. In particular, the absorption of the P-polarized light component in the polarizing plate 23 arranged in the optical path of the blue light is increased, and the temperature rise is also large. Therefore, in this case, it is necessary to make the material of the polarizing plate 23 highly heat-resistant or to increase the air flow from the fan 33 to increase the cooling power.

Next, an example of the configuration of an optical system in the case where the absorption axes of the polarizing plates before and after the liquid crystal light valve are substantially orthogonal will be described. Also in this case, the red light reflecting dichroic mirror 26 and the yellow light reflecting dichroic mirror 2 for combining light are used for the same reason as the case where the absorption axes are substantially parallel.
In No. 9, S-polarized light is used. Since the absorption axes of the polarizing plates before and after the liquid crystal light valve are substantially orthogonal to each other, P-polarized light is used in the process of separating the light from the metal halide lamp 1. In this case, the characteristics of the green light reflecting dichroic mirror 7 and the red light reflecting dichroic mirror 12 are P polarization characteristics shown by the solid line in FIG. Therefore, the S-polarized light component becomes heat at the polarizing plates 15, 19, and 23. Part of the S-polarized light component is reflected off the glass plate 3 and removed. However, the polarizing plate 1 arranged in the optical path of green light and blue light
5 and 23 are irradiated with a lot of S-polarized light and become high temperature.
In particular, the polarizing plate 23 arranged in the optical path of blue light absorbs blue light having high energy, and thus has a large temperature rise. Therefore, it is necessary to make a large hole 25 in the lower light guide 31 so that the air volume from the cooling fan 33 becomes large. Further, the polarizing plate disposed in the optical path of the blue light may be a polarizing plate for high heat resistance. Generally, a polarizing plate has a low polarization ratio of blue light, but a high heat-resistant polarizing plate has a higher polarization ratio of blue light than a general polarizing plate. Therefore, the degree of polarization of blue light can be increased, and there is an effect that a high contrast can be obtained.

In this example, the polarizing plates 15, 19, 23
Since the light directly hits the surface and the temperature rises, these are stuck to the polarizing plate fixing glasses 14, 18, and 22 to prevent deformation. At this time, the light source side of the polarizing plate fixing glasses 14, 18, and 22 is coated with a thin film for preventing reflection. The anti-reflection thin film coating is not applied to the opposite surface to which the polarizing plate is attached. This is because the reflection at the surface occurs only when the refractive index changes greatly from air to glass. That is, the polarizing plate fixing glasses 14, 1
The polarizing plates 8 and 22 are adhered to each other with a resin serving as an adhesive layer, and the change in refractive index is small, so that an antireflection coat is not required. Also, polarizing plates 41, 42, 43 located on the side of the projection lens 32 from the liquid crystal light valve.
Is not attached to the polarizing plate fixing glass because the temperature rise is relatively small.

As a measure against the temperature rise of the polarizing plate, a high heat-resistant polarizing plate is used for the polarizing plates 15, 19 and 23 on the light source side, and a general polarizing plate 41, 42 and 43 for the projection lens 32 is used. A polarizing plate for high contrast may be used.

Further, if the anti-reflection coating is not applied only to the polarizing plate fixing glass 14 arranged in the optical path of the green light, and only the other polarizing plate fixing glasses 18 and 22 are applied with the anti-reflection coating, the green color can be obtained. The amount of light can be reduced compared to the amount of other color light. When such a configuration is adopted for a light source having a large amount of green light component such as the metal halide lamp 1, the color balance of the projected image can be adjusted.

Also, holes 17, 21, 25, 39, 40 are provided in the upper and lower light guides 31, 34 before and after the polarizing plates 15, 19, 23 and the liquid crystal light valves 16, 20, 24. The wind is flowing on both sides of the polarizing plate and the liquid crystal light valve. With such a configuration, the temperature rise of the polarizing plates 15, 19, 23, 41, 42, 43 and the liquid crystal light valves 16, 20, 24 can be reduced, and deterioration due to heat can be prevented.

Next, each dichroic mirror in the example shown in FIG. 1 will be described.

The green light reflecting dichroic mirror 7 reflects only green light out of the light emitted from the metal halide lamp 1. The red light reflecting dichroic mirror 12
Reflects only red light. The mirrors 11 and 28 are reflection mirrors over the entire wavelength range. The red light reflecting dichroic mirror 26 is a mirror that reflects yellow light to red light. By making the dichroic mirror 26 reflect yellow light to red light, green light and red light incident on the red light reflecting dichroic mirror 26 are
It is possible to prevent the red light reflecting dichroic mirror 26 from being discolored due to a change in inclination or variation.

The yellow light reflecting dichroic mirror 29 is
It has the property of transmitting only blue light and reflecting green light and red light. This is for the following reason. The green light and the red light are removed from the white light from the metal halide lamp 1 by the green light reflecting dichroic mirror 7 and the red light reflecting dichroic mirror 12. Therefore, the liquid crystal light valve 24 emits blue to green and orange light. Of these, orange light is unnecessary light for blue light. This is because if the orange light is mixed, the purity of the blue light is reduced, and the light becomes dirty. Therefore, only the blue light is transmitted by the yellow light reflecting dichroic mirror 24.

The blue light transmitted through the yellow light reflecting dichroic mirror 26 is converted into a yellow light reflecting dichroic mirror 29.
Are incident on the projection lens 32 together with the green light and the red light reflected by.

Here, the dichroic mirror group of the synthesizing system is configured so that the blur of the projected image on the screen is minimized. That is, the image of the liquid crystal light valve 16 is
The light passes through the red light reflecting dichroic mirror 26, is reflected by the yellow light reflecting dichroic mirror 29, and is
2 is projected on the screen. At this time, as the light passes through the red light reflecting dichroic mirror 26, astigmatism may occur and the image resolution may be reduced. Further, when the light is reflected by the yellow light reflecting dichroic mirror 29, aberration may occur due to insufficient surface accuracy of the mirror. As described above, the occurrence of aberration due to the light passing through the mirror or being reflected is the same for other liquid crystal light valves. In order to eliminate these aberrations, it is necessary to reduce the thickness of the mirror and increase the area of the reflection surface of the mirror. But both are contradictory. That is, in order to increase the surface accuracy of the mirror, it is necessary to increase the thickness of the mirror. This results in increasing astigmatism due to transmission through the mirror.

In the example shown in FIG. 1, the following configuration is adopted to solve this inconsistency. That is, since the mirror surface accuracy is particularly problematic in the dichroic mirror 29 in front of the projection lens 32, the dichroic mirror 29 is assumed to be thick and have high surface accuracy. On the other hand, the light passing through the dichroic mirror 29 was blue light. This is because blue has the lowest relative luminous efficiency and does not cause much problem even if it is slightly blurred compared to other colors. Since there is no light to be transmitted through the mirror 28, the mirror 28 has a sufficient thickness to provide high flatness. In addition, since the red light reflecting dichroic mirror 26 is slightly farther than the projection lens 32, even if the planar accuracy is lower than that of the dichroic mirror 29, the amount of aberration is small. Therefore, the dichroic mirror 26 is made thinner to reduce the surface accuracy, and blurring of the image of the liquid crystal light valve 16 due to the passage through the dichroic mirror 26 is minimized. As a result, aberrations of the liquid crystal light valves 16 and 20 for modulating green light and red light with high relative luminous efficiency are suppressed, and the resolution of the overall image quality is increased.

As described above, the dichroic mirror 29 closest to the projection lens 32 is made thick and has high surface accuracy, and the other dichroic mirror 26 is made thin and green for large relative luminous efficiency. In this case, a liquid crystal video projector having a high resolution can be obtained. As means for preventing the resolution from being lowered, the liquid crystal light valve 20 is used for green modulation, and the dichroic mirror 26,
Although there is a method of making the thickness of the liquid crystal light valve 29 thick and having high surface precision, as described above, in consideration of the small number of defects required for the light valve for green modulation, the liquid crystal light valve 16 is made to The use of green color modulation has a great effect in that the yield can be substantially improved.

FIG. 9 is a perspective view of a mirror fixing structure of the light separating system of the embodiment shown in FIG. The light separation system refers to the green light reflecting dichroic mirror 7 and the red light reflecting dichroic mirror 12. 52 is a mirror fixing plate, 53 is a dowel for positioning, 54 is a screw hole for fixing to a light guide, 55 is a dichroic mirror, 5
Reference numerals 6 and 57 denote mirror pressing plates. 58 is an incident light beam, 59 is a reflected light beam, and 60 is a transmitted light beam. The dichroic mirror 55 is pressed and fixed to the mirror fixing plate 52 by mirror pressing plates 56 and 57. Its direction is fixed on the opposite side of the incident ray 58. As a result, the window of the mirror fixing plate 52 is closed off, and the reflected light 59 and the transmitted light 60 have the same light distribution around the opening. That is, when the reflected light 59 and the transmitted light 60 are combined again, the periphery of the screen is not colored because the light distribution is the same.

FIG. 10 is a perspective view of the photosynthesis system mirror fixing structure of the example shown in FIG. The photosynthesis system refers to a red light reflecting dichroic mirror 26 and a yellow light reflecting dichroic mirror 29. 61 is a mirror fixing plate, 62 is a positioning dowel, 63 is a screw hole for fixing to a light guide, 64 is a dichroic mirror, 65 and 66 are mirror holding plates, 67 is a screw hole, 68 is incident light A, 69 is Incident light B and 70 are transmitted light and 71 is reflected light. The dichroic mirror 64 is pressed and fixed to the mirror fixing plate 61 by mirror pressing plates 65 and 66. If a double-sided tape is interposed between the dichroic mirror 64 and the mirror fixing plate 61, the dichroic mirror 64 will not be left by an impact.

In this embodiment, each of the incident lights 68 and 69 forms a window of the mirror fixing plate 61. Therefore, the light distribution around the window, which is the opening, is the same for the transmitted light 70 of the incident light A and the reflected light 71 of the incident light B. This means that coloring is eliminated in the peripheral portion of the screen. As described above, as shown in FIGS. 10 and 11, the aperture of the light after the dichroic mirror is set such that the transmitted light and the reflected light are determined by the openings of the mirror fixing plates 52 and 61 in the dichroic mirror 55,
By setting the mirror fixing plate 64 and the mirror fixing plates 52 and 61, there is an effect that coloring due to a poor mixing ratio of three primary colors at the peripheral portion of the screen is eliminated.

Next, the condenser lenses 9 and 10 in the example shown in FIG. 1 will be described. These condenser lenses function to condense the light emitted from the metal halide lamp 1 and reflected by the reflector 1 to the liquid crystal light valves 16, 20, and 24. In this embodiment, the condensing lenses 9 and 10 are replaced with a green light reflecting dichroic mirror 7 serving as a first separating mirror.
And the second mirror, ie, the mirror 11 and the red light reflecting dichroic mirror 12, respectively, so that it is not necessary to provide any space for the condenser lenses 9, 10. In other words, placing the condenser lenses 9 and 10 in the position of the present embodiment has an advantage of downsizing.

Also, from the viewpoint of light collection, the lens becomes brightest by inserting a lens at this position. The reason is that the temperature of the metal halide lamp 1 becomes extremely high, and as a countermeasure, the reflector 2 becomes considerably large. When the reflecting plate 2 is made of glass, the aperture becomes as large as about 80 mm. On the other hand, the polarizing plate and the liquid crystal light valve are weak to heat. As a countermeasure, a glass plate 3 for removing unnecessary polarization components in advance is required. Therefore, the distances between the liquid crystal light valves 16, 20, and 24 and the metal halide lamp 1 and the reflector 2, which are light sources, are considerably long. Generally, the reflecting plate 2 is a parabolic reflecting surface in order to enhance the light collecting property. Further, by setting the light emitting portion of the metal halide lamp 1 as a light source to a position slightly younger than the focal point of the parabola, the condensing diameter can be reduced. However, the distance between the light source and the liquid crystal light valve is long, the opening of the liquid crystal light valve is smaller than the aperture of the reflector 2, and the light emitting portion of the metal halide lamp 1 is not a dot but a line of several millimeters. , Liquid crystal light valve 16, 2
Effective focusing on 0, 24 is achieved by focusing lenses 9, 10
Without it is impossible. The meaning of the condenser lenses 9 and 10 is as follows. First, by placing the light emitting portion of the metal halide lamp slightly before the focal point of the reflector 2, the light is narrowed down to about the opening of the condenser lenses 9, 10.
This is further narrowed down to the size of the openings of the liquid crystal light valves 16, 20, and 24 by the condenser lenses 9 and 10. The effect of this is approximately 1.
The brightness is 5 times or more.

In the structure of this embodiment, the reflector 2 is formed in a parabolic shape, and its f-value is f = 9 mm to 12 mm.
The aperture is set to 65 mm to 85 mm, and the focal point of the parabola and the center of the metal halide lamp 1 are set to the opening side of 2 mm to 4.5 mm. Also, the condenser lenses 9, 10
May be set between a focal length of 100 mm and 250 mm.

FIG. 11 shows the relationship between the distance between the light source and the focal point of the parabola and the brightness in the above configuration. When the light source is close to the parabolic focus, the surrounding brightness comes out, but the overall brightness is insufficient. Also, when the light source is emitted well before the parabolic focus, both the peripheral portion and the overall brightness decrease. The above is the description of the condenser lenses 9 and 10 in the example shown in FIG.

Next, the polarizing plate 15 in the example shown in FIG.
19, 23, the mounting and adjustment of the liquid crystal light valves 16, 20, 24, and the polarizing plates 41, 42, 43 will be described.

As described above, the polarizing plates 15, 19, 23
Because the light hits the light beam directly, the temperature is considerably high. Therefore, the fan 33 is located below the lower light guide 31, and sends cool air to both surfaces of the polarizing plate through the holes 17, 21 and 25 of the lower light guide 31. Then, as shown in FIG. But,
The polarizing plates 15, 19, and 23 may be stopped due to the failure stop of the fan 33 or the like.
It is necessary to fully consider the case where the temperature suddenly becomes hot. Since the polarizing plate is generally a thin resin, it is easily deformed. Therefore, for the protection, the polarizing plate fixing glass 14, 18,
22. Liquid crystal light valves 16, 20,
24 also has a double-sided air cooling structure.

The liquid crystal light valves 16, 20, 24
Focus adjustment for adjusting the distance to the projection lens 32 to be a fixed distance, and pixel alignment so that each pixel of the three liquid crystal light valves fits into one when projected by the projection lens 32. Two adjustments of the adjustment are required.
Of these, focus adjustment is performed on three liquid crystal light valves 1
This is necessary for each of 6, 20, and 24, and the pixel alignment adjustment may be performed by adjusting one liquid crystal light valve with the other two liquid crystal light valves. These adjustment mechanisms will be described with reference to FIG. The distance between the liquid crystal light valve 20 and the projection lens 32 can be adjusted by a focus adjustment screw 35. Also, the liquid crystal light valve 1
The distance between the lens 6 and the projection lens 32 is
8 allows adjustment. Furthermore, the liquid crystal light valve 16 can be moved in the left and right and up and down directions by a left and right direction adjusting screw 36 and a vertical direction adjusting screw 37 in order to match each pixel with the liquid crystal light valve 20. Further, as with the liquid crystal light valve 16, each pixel of the liquid crystal light valve 24 can be matched with the liquid crystal light valve 20.

Since the liquid crystal light valves 20 and 16 are mirror-symmetrical to each other by the red light reflecting dichroic mirror 26, the amount of displacement of the liquid crystal light valve 16 with respect to the liquid crystal light valve 20 is small. Therefore, the adjustment amount of the liquid crystal light valve 16 is
May be set smaller than. Further, since the liquid crystal light valves 20 and 24 are mirror-symmetric with respect to the yellow light reflecting mirror 29, the amount of pixel shift between the two varies greatly depending on the mounting angle of the yellow light reflecting mirror 29. Therefore, the adjustment amount of the liquid crystal light valve 24 may be set large. Further, a mechanism for adjusting the mounting angle of the yellow light reflecting dichroic mirror 29 is provided on the mirror fixing plate 30.
May be provided.

Next, FIG. 12 is a side view of the liquid crystal light valves 16, 20, and 24 in this embodiment, and FIG.
Shown in 72 is a bus substrate, 73 is a TFT substrate, 74 is a counter substrate 75 is a connector, 76 is a black stripe, 7
7 is a close-up. TFT substrate 73 and counter substrate 7
Reference numeral 4 is made using glass as a transparent material as a base material.
On the TFT substrate 73, transistors for switching each pixel are formed. Also, the counter substrate 7
4, a black stripe 76 for protecting the transistor on the TFT substrate 73 from light is formed. The temperature rise in the TFT substrate 73 is caused by the light absorption by the black stripe 76 and the TFT substrate 7.
Third, light is absorbed by the base material of the counter substrate 74.
Therefore, it is preferable to use a substance having a high light reflectance for the black stripe 76. For example, aluminum, nickel and the like. As a result, the temperature rise in the liquid crystal light valve can be prevented, so that a liquid crystal projector with good performance and high reliability can be obtained. Incidentally, a parting-off 77 is formed on the counter substrate 74. In the present embodiment, the partition 77 is formed to cover the entire edge of the counter substrate 74 to protect the transistor formed on the TFT substrate 73 from light.

Finally, the features of the overall configuration of the projector of this embodiment shown in FIGS. 1 and 2 will be described. In the present embodiment, the metal halide lamp 1, the upper light guide 34, the lower light guide 31, a dichroic mirror group housed in the light guide, the projection lens 32
Are all arranged horizontally. The fan 33 for cooling the liquid crystal light valve and the like is connected to the lower light guide 31.
, And a fan 49 for cooling the lamp is arranged on the side of the metal halide lamp 1, the glass plate 3, and the heat ray cut filter 6. According to such a configuration, the height of the device is small and planar, so that a projector excellent in design can be obtained. In addition, since it can be overlapped with a video device and an audio device, it is convenient for installation. Further, the planar shape allows efficient radiation of heat from the upper surface.

In the projector of this embodiment, if the projection lens 32 is directly fixed to the lower light guide 31, the distance between the projection lens 32 and each liquid crystal panel can be accurately obtained. There is a merit that it can be easily done.

[0064]

As described above, the present invention provides a light source,
A first polarization selection element that absorbs light of a specific polarization component of the light emitted from the light source, a light valve that modulates light transmitted through the first polarization selection element, and light emitted from the light valve. A second polarization selection element that absorbs a specific polarization component of the light, and a projection unit that projects light transmitted through the second polarization selection element. The polarization selection element is provided at a position distant from the light valve, and is attached to a fixed plate made of a light-transmitting plate material, whereby deformation of the first polarization selection element due to heat can be prevented.

At this time, if the first polarization selection element is attached to the surface of the fixing plate on the light valve side, the polarized light transmitted through the polarization selection element is directly transmitted without passing through the fixing plate. Since the light is incident on the light valve, it is possible to prevent the polarization state of the polarized light incident on the light valve from changing, and it is possible to obtain a projector with high image quality.

Further, by applying an anti-reflection coating to the surface of the fixing plate opposite to the light valve, it is possible to prevent reflection of light on the surface of the fixing plate and to increase the light use efficiency, so that it is bright. Images can be obtained.

In the above projector, if the first polarization selecting element is a light-resistant polarizing plate and the second polarization selecting element is a high-contrast polarizing plate, the first polarization selecting element due to heat can be used. It is possible to prevent deformation and obtain a projector with high image quality.

In the above projector, when the first polarization selection element, the light valve, and the second polarization selection element attached to the fixing plate are housed in upper and lower light guides, A fan that cools the first polarization selection element, the light valve, and the second polarization selection element is provided below the lower light guide, and the lower light guide has a ventilation hole through which cooling air from the fan passes. With the provision, it is possible to reduce a temperature rise of the polarization selection element and the light valve, and to prevent deterioration of the polarization selection element and the light valve.

At this time, if the ventilation holes are provided on both sides of the fixing plate and the liquid crystal light valve, cooling can be performed efficiently.

Furthermore, if the upper light guide is provided with a ventilation hole through which the cooling air from the fan passes, the cooling efficiency can be further improved.

The present invention also provides a light source, color light separating means for separating light emitted from the light source into red, blue, and green light, three light valves for modulating the respective color lights, The present invention is also applicable to a projector including a color light combining unit that combines the color lights modulated by the two light valves, and a projection unit that projects the light combined by the color light combining unit.

Also in this case, if the polarization selecting element disposed on the light incident surface side of the light valve is attached to the surface of the fixing plate on the light valve side, the polarized light transmitted through the polarization selecting element passes through the fixing plate. Since the light directly enters the light valve without passing through the light valve, it is possible to prevent the polarization state of the polarized light incident on the light valve from changing, and it is possible to obtain a projector with high image quality.

Further, an anti-reflection coating is applied to the surface opposite to the light valve on the fixing plate disposed on the light incident surface side of the light valve for modulating red light and blue light, so that green light is emitted. If the anti-reflection coating is not applied to the fixed plate disposed on the light incident surface side of the light valve to be modulated, an image with good color balance can be obtained when a light source having a large amount of green light is employed. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a projector according to the invention.

FIG. 2 is a perspective view showing an embodiment of the projector according to the invention.

FIG. 3 is a side view of a configuration from a light source to a glass plate of a conventional liquid crystal projector.

FIG. 4 shows an embodiment of the projector according to the present invention.
FIG. 4 is a side view of a configuration from a light source to a glass plate.

FIG. 5 shows an embodiment of the projector according to the invention. FIG. 4 is a side view of a configuration from a light source to a glass plate.

FIG. 6 is a side view of a configuration from a light source to a glass plate in the embodiment of the projector of the invention.

FIG. 7 is an explanatory diagram of polarized light.

FIG. 8 is a characteristic diagram of a dichroic mirror.

FIG. 9 is a perspective view showing a mirror fixing structure of a light separation system in one embodiment of the projector of the invention.

FIG. 10 is a perspective view showing a mirror fixing structure of a photosynthesis system in one embodiment of the projector of the invention.

FIG. 11 is a diagram illustrating a relationship between a light source, a parabola focal length, and brightness in an embodiment of the projector of the invention.

FIG. 12 is a cross-sectional view of a liquid crystal light valve in one embodiment of the projector of the present invention.

FIG. 13 is a plan view of a liquid crystal light valve in one embodiment of the projector of the present invention.

[Explanation of symbols]

 1,44 ... Metal halide lamp 2,45 ... Reflection plate 3,46,47,48,50 ... Glass plate 4 ... Glass plate case 5 ... Heat radiation fin 6 ... Heat-cut filter 7 ... green light reflecting dichroic mirror 8, 13, 27, 30, 52, 61 ... mirror fixing plate 9, 10 ... condensing lens 11, 28 ... mirror 12, 26 ... red light Reflective dichroic mirrors 14, 18, 22 ... Polarizing plate fixing glass 15, 19, 23, 41, 42, 43 ... Polarizing plates 16, 20, 24 ... Liquid crystal light valves 17, 21, 25, 39 , 40 ... hole 29 ... yellow light reflecting dichroic mirror 31 ... lower light guide 32 ... projection lens 33, 49, 51 ... fan 34 ... upper light guide 35, 38 ... Focus adjustment screw 36 ... horizontal adjustment screw 37 ... vertical adjustment screw 53, 62 ... positioning dowel 54, 63, 67 ... screw hole 55, 64 ... dichroic mirror 56, 57, 65, 66: mirror holding plate 58: incident light 59: reflected light 60: transmitted light

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location G03B 33/12 G03B 33/12

Claims (10)

[Claims] 1. A light source, a first polarization selection element that absorbs light of a specific polarization component among light emitted from the light source,
A light valve that modulates light transmitted through the first polarization selection element, a second polarization selection element that absorbs light of a specific polarization component of light emitted from the light valve, and the second polarization A projection unit for projecting light transmitted through the selection element, wherein the first polarization selection element is provided at a position distant from the light valve, and is attached to a fixed plate made of a light-transmitting plate material. A projector characterized by being attached. 2. The projector according to claim 1, wherein the first polarization selection element is attached to a surface of the fixing plate on the light valve side. 3. The projector according to claim 2, wherein an anti-reflection coating is applied to a surface of the fixed plate opposite to the light valve. 4. The method according to claim 1, wherein the first polarization selecting element is a light-resistant polarizing plate,
Wherein the polarization selecting element is a high-contrast polarizing plate. 5. The light guide according to claim 1, wherein the first polarization selection element, the light valve, and the second polarization selection element attached to the fixing plate are housed in upper and lower light guides. A fan for cooling the first polarization selection element, the light valve, and the second polarization selection element is provided below the lower light guide, and cooling air from the fan is provided in the lower light guide. Characterized by having a ventilation opening through which air passes. 6. The projector according to claim 5, wherein said ventilation holes are provided on both sides of said fixed plate and said liquid crystal light valve. 7. The projector according to claim 5, wherein the upper light guide is provided with a ventilation port through which cooling air from the fan passes. 8. A light source and a light emitted from the light source,
A color light separating unit that separates blue and green light, three light valves that modulate the respective color lights, a color light combining unit that combines the color lights modulated by the three light valves, and a color light combining unit. Projection means for projecting the combined light, a light selection surface for absorbing light of a specific polarization component is arranged on the light incident surface side of each light valve,
The projector, wherein the polarization selection element is provided at a position distant from the light valve, and is attached to a fixed plate made of a light-transmitting plate. 9. The projector according to claim 8, wherein the polarization selecting element is attached to a surface of the fixing plate on the light valve side. 10. The fixing plate according to claim 9, wherein the fixing plate disposed on the light incident surface side of the light valve for modulating red light and blue light has an antireflection coating on a surface opposite to the light valve. The projector, wherein the fixed plate disposed on the light incident surface side of the light valve that modulates green light is not coated with an anti-reflection coating.